168 THE GENESIS OF SPECIES. [CHAP. 



batrachians, as similar to each other as are some of the frogs 

 of South America and of Europe. At the same time such 

 phenomena must at present be considered as very improb- 

 able, from the action of ancestral habit, as before stated. 



We have seen, then, that the geographical distribution 

 of animals presents difficulties, though not insuperable ones, 

 for the Darwinian hypothesis. If, however, other reasons 

 against it appear of any weight if, especially, there is 

 reason to believe that geological time has not been sufficient 

 for it, then it will be well to bear in mind the facts here 

 enumerated. These facts, however, are not opposed to 

 the doctrine of evolution ; and if it could be established 

 that closely-similar forms had really arisen in complete in- 

 dependence one of the other, they would rather tend to 

 strengthen and to support that theory. 



